1. Field of the Invention
This invention relates to a communication system consisting of a card-like device and a communication apparatus which receives data from the card-like device.
2. Description of the Related Art
Heretofore, there have been systems which utilize portable external memories, such as IC cards.
There has, for example, been a system in which telephone numbers for abbreviated dialing are registered in an IC card, and calling is performed by connecting the IC card to a telephone set. However, since such an IC card is mechanically connected to the telephone set, there is the disadvantage that a connecting portion of the IC card is mechanically deteriorated by repeating the connection.
There has also been a system in which an acoustic coupler is provided in a portable electronic computer or the like, and a dial number previously registered in the portable electronic computer is transmitted from the acoustic coupler as a PB (push-button) tone. This kind of device performs calling by transmitting the PB tone from the transmitter of a telephone set to a central control.
Such a portable device incorporates a power supply, such as a lithium battery or the like.
When the device performs the function of data holding, calculation or the like in a portable state, only a small amount of power is needed. However, when it is intended to execute additional functions, power consumption increases, and hence there is the possibility that the exhaustion of the battery will frequently occur. Thus, there is the disadvantage that reliability cannot be maintained.